I think that the amount of N/A power they make combined with the suspension and brakes it is the best one to ever hit the road. The powerband seems to be a lot more street and user friendly, too, compared to the ZR1 from what I read here and there.
Not sure why you think that the magnetic ride suspension and powerband of the supercharged C7Z is inferior to those same aspects of the C6Z.
The 6 is more of a raw car than the 7, but when properly operating (eg. not overheating) the 7 is superior in every aspect.